Purpose Endovascular treatment (ET) in patients with large vessel occlusion stroke
(LVOS) with unknown onset or an extended time window can be safe and effective if
patients are selected by defined clinical and imaging criteria; however, it is unclear
if these criteria should also be applied to patients with unknown onset and unknown
time last known well. In this study, we aimed to assess whether absent information
on the time patients were last known to be well impacts outcome in patients with unknown
onset LVOS. Methods We analyzed patients who were enrolled in the German Stroke Registry-Endovascular
Treatment between 2015 and 2019. Patients with unknown onset and unknown time last
known well (LKWu) were compared to patients with known onset (KO) and to patients
with unknown onset but known time last known well (LKWk) regarding clinical and imaging
baseline characteristics and outcome. Results Out of 5909 patients, 561 presented
with LKWu (9.5%), 1849 with LKWk (31.3%) and 3499 with KO (59.2%). At 90 days, functional
independency was less frequent in LKWu (27.0%) compared to KO (42.6%) and LKWk patients
(31.8%). These differences were not significant after adjusting for confounders. A
main confounder was the initial Alberta stroke program early CT score. Conclusion
The LKWu patients had a similar outcome after ET as KO and LKWk patients after adjusting
for confounders. Thus, ET should not be withheld if the time last known well is unknown.
Instead, LKWu patients may be selected for ET using the same criteria as in LKWk patients.